Generally, a closure for a container of the type as described above comprises a tab which is attached at the tab body by rivet means to the closure. The rivet means should be such that the tab is reliably attached to the closure and will not fail or even release during the lifting or tearing of the closure part during the opening of the container and thereby being separated in an undesired manner from the closure part. Such a situation is not desired and even dangerous because generally the torn score line comprises a sharp torn edge.
For a reliable and easy popping open of the closure it is preferred that the area where the initial opening of the closure occurs is relatively stiff because a stiff will be easier to pop open than a flexible closure. However, due to the structural elements present in the closure for attaching the tab via the rivet means to the closure part this area of the closure is generally stretched and relatively thin and vulnerable, particularly when the rivet means are made from the closure part material and are integral with the closure part. In addition, when the content of the closure is pressurized, it should be avoided that when having a weaker area an undesired opening by peaking could occur.
The above considerations require a tab to be reliably attached by the rivet means to the closure part, for having an easy opening of the container with the tab and without a tool. Preferably such container is also suitable for containers comprising pressurized contents. In view of these considerations, the skilled person will acknowledge that the area were the tab nose will act on the score line for popping open the closure and forming a so-called opening chord along the score line, is an area full with compromises for balancing conflicting constructional features. The closure should be easily opened but still sufficiently rigid for withstanding internal pressures and easy popping. Therefore, this delicately designed area is unlikely for the skilled person to include or be imparted further construction measures in relation to an improvement of the opening of a closure as described above, but which may interfere with the existing easy opening construction.